Bloch MB-150; a rarity?...of course

[Llaut Mallorquin]

Can someone explain this? Why is it crooked? Moments of inertia of the motor?
Would it influence the handling of the plane?
Apparently the plane was actually like that
Thanks and best regards

[ContourCraig]

Rotary engines tend to act like gyroscopes, which cause the platform (the airframe) to go in different direction to which the pilot intends. Offseting the engine at an angle helps the plane fly straighter. It was very common in WW1 aircraft to perform differently in different turns to port or starboard.

[Llaut Mallorquin]

Thank you very much for the answer, ContourCraig this confirm my suspicions. The look of the engine fairing is still shocking
Regards

[RyanShort1]

Originally Posted by ContourCraig

Rotary engines tend to act like gyroscopes, which cause the platform (the airframe) to go in different direction to which the pilot intends. Offseting the engine at an angle helps the plane fly straighter. It was very common in WW1 aircraft to perform differently in different turns to port or starboard.

I think that's a radial, not a rotary, though. Propellers act as gyroscopes when they are deflected by control inputs, but this is probably something more related to other aerodynamic factors rather than just gyroscopic effects.

Technique - Left Turning Tendencies - AOPA

[Butelczynski]

Gyroscopic force of a propeller is a force not to be underestimated. There are many ways that have been tried to counteract it and this is one of them.Not particularly successful one since that Bloch fighter family was the only one that was produced afaik.

Propellers today are far lighter and far more efficient than ever so this is not an issue anymore.

[Isaac]

Originally Posted by Llaut Mallorquin

Can someone explain this? Why is it crooked? Moments of inertia of the motor?
Would it influence the handling of the plane?
Apparently the plane was actually like that
Thanks and best regards

Very common to many propeller planes. Almost all the free flight and early Radio Controlled models had a left angle ( or right depending on propeller rotation and also down somewhat ). This is to counter the torque generated by the prop.


and no, this is a radial engine and not a rotary engine, so the only swing was from the propeller and not the engine.

Lastly, there was another aero treatment to high torque generated by the engine at low aero speed and that was to add more wing area on the opposite wing tip. Case in point is the Macchi 205 Veltro. The wings are not symmetrical left to right sides. The left wing is longer than the right.


Isaac

[CharlieC]

Another solution to the torque problem of high powered propeller aircraft is to offset the rudder or build in a few degrees of turn into the fin. I guess the French just had to be different.

Regards,

Charlie

[Llaut Mallorquin]

I was surprised that it was a rotary engine. I had a two-cylinder motorcycle (Guzzi) with a transverse V-engine and when starting or accelerating from a standstill, with dead point, the bike leaned to the right due to the engine torque. When I was ridding the motorcycle, the aforementioned effect disappeared completely


"Lastly, there was another aerodynamic treatment for the high torque generated by the engine at low airspeed and that was adding more wing area at the opposite wingtip. A good example is the Macchi 205 Veltro. The wings are not symmetrical from left to right. The left wing is longer than the right".


Yes, I already knew this, but it certainly seems safer to me that the design compensation is due to the gyroscopic effect of the propeller when turning. Thank you all for the explanations

[Isaac]

Originally Posted by Llaut Mallorquin

I was surprised that it was a rotary engine...............

Once again. The Bloch 150 did NOT have a rotary engine. It had a radial engine!

Radial engines do not rotate. They are fixed to the aircraft via engine mount.


Rotary engines were used in WW1 and the shaft was attached to the fuselage. The propeller was attached to the engine body ( not the shaft ) and both rotated. This was to aid the cooling of the engine cylinders. That is why there was so much inertia generated that effected the aircraft performance.


Isaac

[AgaPablo]

Originally Posted by CharlieC

Another solution to the torque problem of high powered propeller aircraft is to offset the rudder or build in a few degrees of turn into the fin. I guess the French just had to be different.

Regards,

Charlie

Good point Charlie C. I came to know this feature following a building thread of a Corsair, unlike plastic models, where this detail is lost, GPM`s Corsair reproduces it accurately. Of course, the modeller had to clearly state that he had not fouled the fuselage but followed the rules to the letter.
Some years later, I went through the MB151 and had to give the same explanations...